fix(web): use a brain icon for the effort dropdown

[t3-code]

the compact effort dropdown used a speedometer, which reads as speed rather than reasoning effort. replace it with lucide's brain icon in both codex and other-provider layouts.

fast mode still uses the existing lightning bolt. sizing, colour, tooltip, accessible name, menu behaviour and responsive layout are unchanged. this affects the shared web/desktop composer; native mobile is unchanged.

verification

• 10 existing TraitsPicker tests passed.
• web typecheck, targeted lint/format checks and git diff --check passed.
• no new tests for an icon-only swap.
• the image below is the approved screenshot mockup, not a running-app capture. a live-app visual pass has not been performed.

before / proposed appearance

request provenance

requested by @extoci.

built with gpt-6-astra in hermes agent.

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.5 KiB	13.5 KiB	+12 B (+0.1%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.1 KiB	7.1 KiB	−2 B (−0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.4 KiB	6.4 KiB	+14 B (+0.2%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	56.2 KiB	56.3 KiB	+44 B (+0.1%)	66.4 KiB	✅
Codex	Live turn messages	9	10	+1 (+11.1%)	21	✅
Claude	Total thread wire	13.5 KiB	13.5 KiB	+2 B (+0.0%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	+5 B (+0.1%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.4 KiB	6.4 KiB	−3 B (−0.0%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.0 KiB	57.0 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	9	9	0 (0.0%)	21	✅

Baseline: f5ef0dd · PR result: 28b58a9 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 114.0 KiB
• Claude decoded thread snapshot: 114.6 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

[macroscopeapp]

Approvability

Verdict: Approved at 28b58a9

Macroscope's review found this PR approvable — This PR only swaps the effort dropdown’s existing speedometer icon for a brain icon in two already-supported layouts. It leaves selection defaults, interaction behavior, accessibility labels, sizing, and menu logic unchanged.

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